child widget fit parent width flutter code example

Example 1: flutter container width of parent

width: double.infinity,
  height: double.infinity

Example 2: flutter set widget width to 50% o parent

@override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("MediaQuery"),
      ),
      body: Container(
        width: MediaQuery.of(context).size.width * 0.5,
        height: MediaQuery.of(context).size.height * 0.5,
      ),
    );
  }